forum.vdsworld.com

GeoTrail · Posted: Sun Mar 16, 2003 3:41 am Post subject: Why does this overwrite?

I'm experimenting with the list command and I'm wondering about something. When I don't have anything selected in the list, type in a name and click the button then it gets added to the list.

But when I have a name selected and enter a name and click the button the name I entered overwrites the one in the list.

How can I avoid this?

Mac · Posted: Sun Mar 16, 2003 4:06 am Post subject:

To ADD items to a list, use LIST ADD.

LIST PUT will overwrite the item at the current index pointer.
LIST INSERT will insert the data in at the current index pointer.

Cheers, Mac Smile

ShinobiSoft · Posted: Sun Mar 16, 2003 4:07 am Post subject:

The list put command does just that, it puts the new text where the pointer
index to the current selection is. To append or add something use "List add,...".
To insert somthing use "list insert,..." and the new inserted text will be inserted before the current index position. Smile

ShinobiSoft · Posted: Sun Mar 16, 2003 4:08 am Post subject:

Darn it Mac Evil or Very Mad

Mac · Posted: Sun Mar 16, 2003 4:09 am Post subject:

Also - ya can't use LIST PUT or LIST INSERT with SORTED lists... Wink

Cheers, Mac Smile

GeoTrail · Posted: Sun Mar 16, 2003 4:50 am Post subject:

OK, thanks for that guys.

And Mac, using LIST PUT on that sorted list works perfectly here Wink

Mac · Posted: Sun Mar 16, 2003 4:55 am Post subject:

Not my idea - this is from the VDS 3 help file:

PUT is used to write the specified text to the position in the list indicated by the index (pointer). PUT lets you treat a list as a random access file. Note that you cannot use PUT with sorted lists.

Copyright ©1995 - 2000 S.A.D.E. s.a.r.l. / All rights are reserved.

Cheers, Mac Smile

FreezingFire · **Admin Team** Joined: 23 Jun 2002 Posts: 3508

Same thing from the VDS 4 help file:

GeoTrail · Posted: Sun Mar 16, 2003 4:44 pm Post subject:

Yes I see that.
But why does this work then?

Mac · Posted: Sun Mar 16, 2003 10:20 pm Post subject:

SADE prolly put that in the help file for a reason. For example,
it may get flaky on larger lists, or may conflict with something
you haven't tried yet, or may act differently on another OS, etc.

It's usually a pretty good idea to heed a developer's warning
when they say you CANNOT or SHOULD NOT do something. Wink

Cheers, Mac Smile

ShinobiSoft · Posted: Sun Mar 16, 2003 10:34 pm Post subject:

I couldn't agree with Mac more. It's the same with any warnings that I
might put in one of my dlls. I put those warnings there for a reason. Mainly
to prevent any undesirable operations. SSTreeVw.dll is a good example.
Because using the CLICK and DBLCLICK styles together on the same
treeview control produces undesirable results, I suggested not to use those
two styles together. Mainly, because the DBLCLICK event actually generates
two events, and the first event will be interpreted as a CLICK event even
though it's a double click.

Another thing about "List put", is it's used to rewrite an existing list item,
where as "List add" is used to append a new item to a list and "List insert"
is used to insert a new item before the list index pointer.

"List put" is generally used when using a list in a random access kind of
manner.

GeoTrail · Posted: Mon Mar 17, 2003 2:07 am Post subject:

OK ok ok. I give Confused

But I'm gonna try it on my laptop which is running Windows 95 a, and if it works there, then I'm gonna use it Wink

Didn't mean to start something here. Just wanted to get some answers.
And what both you guys said makes sence. Very Happy

Mac · Posted: Mon Mar 17, 2003 3:27 pm Post subject:

No problem GeoTrail, Smile

Trying/discussing different stuff is how we come up with a lot of
cool programs. Wink

However...

Since a sorted list automatically re-arranges data (sorts alphabetically),
direct item manipulation could result in replacing/corrupting the wrong
item when the list sorts during the process (in a loop for example).

I would ask that ya do one thing - if ya post any code using LIST
PUT on sorted lists, please mention it in the code description so
users can be made aware of it. Wink

Cheers, Mac Smile

vdsalchemist · Posted: Mon Mar 17, 2003 3:39 pm Post subject:

Hi GeoTrail,
In my experience with VDS List's. I have always found when using List Put that you should set the index pointer first to the item that you want to overwrite. It will keep the List command from overwriting something that it should not be overwriting. If all your doing is adding items to a list then just use List Add. The list add command takes no more work than the list put and list add will always place the item as the last item unless the list is a sorted list then you can use @index() to get the current index.
As you work more and more with VDS you will find that when the help file says a command or function is only used for this reason then usually it is very literal about that. VDS is a very literal language and the commands and function names are very literal about what they are for and do. That is part of the power of VDS and what makes it the fastest development environment on the Net...

GeoTrail · Posted: Mon Mar 17, 2003 5:29 pm Post subject:

Yeah, you are both right guys *hitsmyself* Embarassed

I've never thought about it that way, and I really can't argue with what you both said, so I guess I just have to follow your path Wink

c:\windows\system32 was it? Laughing